deHavilland
Electrical
How is superheated steam produced after the steam generator? does it pass through a heat exchanger? If so what is used as the heateing matierial in a nuclear plant?
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Super heated steam 1
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TheBlacksmith
Mechanical
Nuclear plants, to my knowledge, all use saturated (wet) steam. There was one Soviet warship that used a oil fired superheater to attain full speed as the nuclear reactor was undersized for the task. Note I said one ship.
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The steam itself is used in secondary heat exchangers to reheat cooler steam. Wet steam would destroy the turbines.
After the steam generators have created the steam, it passes through a series of moisture separators to dry the steam before going to the high pressure turbine. Some of this main steam is bled off and passed through moisture separator-reheaters(MSRs). The steam that has passed through the high pressure turbine then travels to the shell side of the MSRs where it is reheated and again passes through a series of chevron dryers to remove any moisture before going to the low-pressure turbines. Steam is extracted at various stages of each turbine for feedwater heating.
After the steam generators have created the steam, it passes through a series of moisture separators to dry the steam before going to the high pressure turbine. Some of this main steam is bled off and passed through moisture separator-reheaters(MSRs). The steam that has passed through the high pressure turbine then travels to the shell side of the MSRs where it is reheated and again passes through a series of chevron dryers to remove any moisture before going to the low-pressure turbines. Steam is extracted at various stages of each turbine for feedwater heating.
Most reactor plants produce dry non superheated steam,
for light water PWR's the steam generators are well mixed and use a steam head on top of the primary U-tubes.
Candu Heavy water reactors circulate water which turns into a water-steam mixture inside the reactor traveling through tubes and is separated in an external steam head. The same method was used for the RBMK (in Russia) and other graphite moderated reactors in the US.
BWR, the steam head is incorporated into the top of the reactor of course.
The one exception was the Babcox and Wilcox units. The water to steam loop flowed upward through a once through steam generator, while on the primary side the high pressure reactor water flowed downwards, result 50 to 100 degrees of superheat, the turbine plant still used moisture separator re-heaters on the low pressure turbine feed, but less steam was needed for the reheat and the high pressure turbine had less water to contend with.
The downside of this design was there less water inside the steam generator which provided less of a heat sink during plant upsets. Three Mile Island was one of the few plants of this design and the lack of a large heat sink contributed to the plant's unit II demise.
Also the feed water needed to be very clean or else scale would build up in the steam generator
Hydrae
for light water PWR's the steam generators are well mixed and use a steam head on top of the primary U-tubes.
Candu Heavy water reactors circulate water which turns into a water-steam mixture inside the reactor traveling through tubes and is separated in an external steam head. The same method was used for the RBMK (in Russia) and other graphite moderated reactors in the US.
BWR, the steam head is incorporated into the top of the reactor of course.
The one exception was the Babcox and Wilcox units. The water to steam loop flowed upward through a once through steam generator, while on the primary side the high pressure reactor water flowed downwards, result 50 to 100 degrees of superheat, the turbine plant still used moisture separator re-heaters on the low pressure turbine feed, but less steam was needed for the reheat and the high pressure turbine had less water to contend with.
The downside of this design was there less water inside the steam generator which provided less of a heat sink during plant upsets. Three Mile Island was one of the few plants of this design and the lack of a large heat sink contributed to the plant's unit II demise.
Also the feed water needed to be very clean or else scale would build up in the steam generator
Hydrae
I seem to recall that the Indian point unit 1 reactor used an oil fired superheater to improve the steam turbine cycle heat rate.
The nuclear steam side of the cycle was saturated, but the HP main steam was superheated in a seperately fired superheater.
The nuclear steam side of the cycle was saturated, but the HP main steam was superheated in a seperately fired superheater.
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